Alloys



" Patented Feb. 4-, 1941 UNITED STATES PATENT OFFICE ALLOYS Reginald 8.Dean, Washington, D. C., assignor to Chicago Development Company,Chicago, 111. a

corporation of Illinois No Drawing. Application July 8, 1939,

' Serial No. 283,464

6 Claims. (Cl. 75-178) liliy-invention relates to alloys .of copper,zinc n'd manganese and is a continuation-in-part of V 'r'ny priorapplication Serial No. 199,329, filedApril duction of hard, high tensilestrength casting al-' 10 loys which may be produced relativelyinexpensively, although many of the alloys within the composition rangepointed out hereinbelow may be used for other purposes.

More specifically, my present invention relates to alloys containingrelatively high proportions of zinc and ratios of manganese to copper ofat least unity, and particularly relatively high ratios of manganese tocopper. The alloys fall within the general range 2% to copper, to zinc,and the balance substantially manganese, in each case, however, themanganese being present in amounts at least equal to, and preferablysubstantially greater than, the copper. Small proportions of otheralloying constituents may be utilized where special characteristics aredesired, but, in general, the alloys contain substantially only copper,zinc and manganese, such other elements as are present being introducedonly as impurities. I may point out at the outset, however,.

that, for best results, the manganese employed should be electrolyticmanganese or other highly pure manganese containing, preferably, notmore than 0.1% of other metals as impurities, and the copper and zincused should also be of highly pure grade.

At least most of the alloys in the composition range identified aresomewhat ductile and very hard and strong. They may be produced inaccordance with various procedures, but the most suitable and dependablemethod isfirst to-prepare an alloy of zinc and copper and sukequentlyadd the manganese in theform of a fairly fine powder. I have found thatif the substantially molten mixture is stirred at a temperature slightlybelow the boiling point of zinc, a homogeneous alloy is readilyproduced. While any manganese of high purity, that is, containing notmore than about 0.1% of metallic impurities, may be used in theproduction of useful alloys in accordance with my invention, for thebest results, I

as previously noted, electrolytic manganese should be utilized bothbecause of the relatively great readiness with which the alloys are madein accordance with the preferred process and also because of theespecially satisfactory properties of the alloys made with electrolyticmanganese so far as ductility and toughness are concerned.

Example 1.In accordance with one example, I melttogether parts zinc and15 parts cop- 5 per, and, while maintaining the mixture in asubstantially molten condition but below the boiling point of zinc, Istir in 25 parts relatively finely divided electrolytic manganese. Whenhomogeneity-is obtained, the alloy is cast in in- 10 gots or it may becast directly into sand or chilled molds or in a'die casting machine.The alloy so produced contains about 20% 'manganese, about 68% zincand'about 12% copper. It has a hardness greater than Rc-15 as cast and atensile strength greater than 150,000 pounds per square inch. Some ofthe additional properties and uses of alloys of this composition will bediscussed hereinafter.

Example 2,- parts zinc and 10 parts copper are heated to about 870degrees C. and 50 parts finely divided electrolytic manganese areintroduced, with stirring, maintaining the temperature of the mixturebelow the boiling point of zinc. The alloy so produced contains about60% zinc, about 6%% copper, and about 33%% manganese.

Example 3.6 parts copper and 94 parts zinc are heated together inaccordance with the pre- 30 ceding example, and parts of electrolyticmanganese are introduced. Following the procedure outlined in thepreceding examples a highly useful alloy is produced containing about50% manganese, 3% copper and 47% zinc.

Example 4.12 parts copper and 88 parts zinc are heated together andparts finely divided electrolytic. manganese are gradually introduced,maintaining the temperature slightly below the, boiling point of zincand continuing heating and stirring until a homogeneous mixture isproduced. The molten mixture either may be cast into ingots or directlyinto molds for the production of castings. The alloy so'producedcontains 35.2% zinc, 60% manganese and 4.8% copper. 45

Preferably following the general procedure given in the precedingexamples, alloys of various combinations of zinc-copper-manganese may beproduced. At least most of them are suitable for die casting or forcasting in chilled or sand molds. 50 The alloys so produced are, ingeneral, readily machined, have a beautiful silver color, and are highlyresistant to corrosion either by atmospheric conditions or by saltwater. The hardness of at least most of the alloys ranges from Etc-15 5tom-25. and the tensile strength from 150,000

pounds per square inch to 250,000 pounds per square inch. The elongationin two inches varies, in general, from 5% to 10%.

Within the composition range given, the higher zinc alloys, especially,for example, alloys containing of the order of about to zinc, about 20%manganese and about 10% to about 15% copper, are of great use in makingall sorts of hardware and decorative objects. In this particular range,the objects produced are, moreover, relatively inexpensive due to thepresence of the large proportion of the relatively cheap metal zinc. Thealloys in this range may be produced with considerable advantageoverother alloys having properties which render them suitable for thesame general purposes.

The utility of the alloys of the present invention is by no meansconfined to such materials as hardware and decorative objects.Particularly when the proportion of manganese is at least about 20% andsomewhat higher than 20%, and, for that matter, throughout the rangegiven, castings of great strength and hardness are produced which arehighly resistant to corrosion and, therefore, have-great advantage wheresuch combinations of properties are required. Examples are parts ofmarine pumps and various valves and gears which are subjected tocorrosive conditions.

While the alloys of my present invention are primarily designed for useas castings, some of them are sumciently ductile so that various typesof forming operations may be utilized in manufacturing finished parts.The great tensile strength and hardness of the castings, however,

makes it possible to'employ the alloy as cast for large numbers ofmechanical purposesyandwhere finished surfaces are necessary, as invalves and gears, or the like, the easy machineability of the castingsmakes it possible to finish them from the casting to any final shapedesired. In using the alloys, they may be cast to shape as meltedinitially, or the ingots may be produced and subsequently remelted forproduction of castings.

What I claim asnew and desire to protect by Letters Patent of the UnitedStates is:

1. An alloy of 3.0% to zinc, 2% to 15% copper. and balance substantiallypure manganese, the manganese being present in proportions at leastequal to that of the copper.

2. A casting alloy containing about 70% zinc,

about 20% manganese, and about 10% copper.

3. A casting alloy containing about 70% zinc, about 20% electrolyticmanganese, and about 10% copper.

4. A deformable alloy of manganese, zinc and copper, having a hardnessof at least Rc-15 in the cast condition, said alloy containing fromabout 10% to about 15% copper, from about 65% to about 70% zinc, and thebalance substantially pure manganese.

5. -An alloy of zinc, manganese and copper particularly suitable for theproduction of tough castings, said alloy comprising about 65% zinc,about 20% manganese and about 15% copper.

6. An alloy, particularly adaptable for castings, comprising 2% to 15%copper, 30% to 75% zinc, and-the balance substantially electrolyticmanganese, said manganese being present in proportions at least equal tothat-of the copper.

. REGINALD S. DEAN.

